Known endorsers for printing information either on the front or rear sides of documents such as checks have generally provided for the printing of fixed or constant information by means of a rotating legend-carrying print head that serves to impress an inked ribbon into contact with the document. Other of these known endorsers have provided for the printing of variable information by means of such complex devices as ink jet printers wherein uniformly sized droplets of ink are pressurably ejected from a nozzle and variably deflected electrostatically or magnetically in free flight towards the moving document, the movement of the document in concert with the variable vertical sweeps of the droplet stream serving to form the individual characters of the variable information.
The prior art fixed information endorsers, in addition to being ineffective for printing variable information, have generally required inked ribbons and their associated troublesome and space-taking feed and reverse mechanisms, and the prior art variable information endorsers, although appropriate for use in large scale document processing equipment, have generally proven to be too expensive for use in smaller scale cost effective special purpose equipment such as document encoders, the primary objective of such special purpose equipment being the preliminary encoding and sorting of documents preparatory to subsequent automatic processing.